Fuel supply system



F. EARFQ ET AL FUEL SUPPLY SYSTEM Filed June 6. 1946 EM/L O. Wwf/7. y li #fram/ax Patented Nov. 2,

UNlTso s'rATl-:s f PATENT OFFICE,-

2,452,627 FUEL SUPPLY SYSTEM Frederik nai-roo ami amil o. Wirth, southnena End., assigriors to Bendix Aviation Corporation,

Southend, End., a corporation of Delaware application .lune 6, 1946,Serial No. 674,868y

(Cl. 12S-119) provide a fuel supply system for an internal combustionengine or the like, wherein the ratio of fuel-to-alr mixture isregulated in accordance with engine speed as modified by a manuallyactuated control.

Still another object of the invention is to provide a fuel supply systemwherein the discharge of fuel into the induction passage-of the engineis regulated in accordance with engine speed and throttle position.

Still another object of the invention is to provide a fuel supply systemwherein a controlled supply of fuel to the engine is obtained byregulating the effective fuel metering head across a metering jet inaccordance with variations in engine speed and air throttle position.

`Another object of the invention is the incorporation of an improvedsimplified priming device in fuel supply systems of the aforesaid typeto facilitate starting of the engine.

To realize these and other objects which will be apparent from thefollowing description, the

present invention includes, in a fuel supply sys-y tem, a conduit inwhich are disposed an enginedriven centrifugal pump for varying thepressure of unmetered fuelln the conduit in accordance with enginespeed, a jet for metering the fuel delivered by the pump 'and a meteringhead control unit communicating with the inlet and outlet passages ofthe centrifugal pump, the pressure of the fuel in the control unit beingregulated by the throttle valve actuating means. A fuel discharge nozzleisprovided in which the effective area of the nozzle is automaticallyvaried to maintain the meteredfuel pressure in accordance with thepressure in the control unit, the metered fuel pressure as determined"by the control unit pressure and the unmetereci fuel pressure asdetermined by the centrifugal pump jointly controlling the quantity offuel supplied to the engine. The fuel system disclosed in this case isclaimed broadly in our copending application Serial No. 607.290.

`The fuell supply system hereinafter more fully described is not limitedto the particular embodiment disclosed in the specification and drawingbut is understood to be available in many cases where a fuel supplysystem for controlling the ratio of fuel-to-air mixture in accordancewith engine requirements is desirable. It is our intention to utilizeany or all variations that properly fall within the scope of theappended claims.

A diagrammatical view of the fuel system is shown in the figure whereinii designates a carburetor body, l0 aninduction passage, I2 an intakemanifold, it a throttle valve, I6 a fuel regulator unit and i8 a pumpfor delivering the fuel l to the system at a substantially constantpressure.

A supercharger may be included in the system between the inductionpassage Iii and intake manifold l2 or as an alternative, it may beconnected to the intake side of the induction passage. The pumpgenerally indicated at i8 is provided for supplying liquid fuel from asource to the system preferably at a substantially constantpredetermined pressure and consists of a stator 2B, a rotor 22 disposedtherein and having, as shown in 'the drawings, four spring loaded vanes2d for contacting the peripheral surface of the stator 20. In operation,the fuel is drawn into the pump through intake 26 and discharged throughoutlet 28, the pressure being controlled by a bypass conduit 30regulated by a pressure responsive valve 32, so situated as to controlcommunication between inlet conduit 26 and by-pass 30, urged to itsclosed position by calibrated spring 33, The fuel is delivered from theoutlet 28 of the pump through conduit '3d to inlet passage 36 of theregulator unit i6.

The fuel entering regulator unit I6 from pump lil passes through conduit36 and passage 38 to pump t0. The pump which is of the centrifugal typeconsists of an impeller lf2 having blades t3 disposed in chamber it anda shaft lili rotatably mounted in body of regulator unit I6, joined tothe impeller and connected by any suitable means to the engine which,though not shown in the drawing, rotates the impeller at a speed 'indirect proportionto the R. P. M. thereof to build up an outlet pressurefor the metering headof the system. The outlet of pump di) is connectedto conduit 4B which throughV metering jet 50`communcates with chamber 52in the wall of body 8. The pressure in chamber 52 is at all times duringengine operation less than-the pressure anterior to the metering jet 50,the difference therebetween being the effective metering head across themetering jet 50. Chamber 52 communicates end of throttle shaft B8.

with the discharge nozzle 56 extending into the induction passageposterior tothe throttle valve Il. A 'passage 56 leading from the intakeside of the impeller and having restriction 58 therein communicates withchamber 60 in casing 62 which is separated from chamber 52 by a fuelimpermeable flexible diaphragml, preferably having a substantiallyinflexible central portion 66 provided with a flat side adjacent theinlet to nozzle 54. I'he central portion 66 is adapted to fluctuate withthe diaphragm in response to variations in pressure on either sidethereof and to'variably lregulate the effective area of the inlet tonozzle l to thereby regulate the discharge of fuel according to saidpressure variations. A relatively weak calibrated spring 61 seated in acup-shaped portion of casing 62 is provided to yieldingly urge thecentral portion 66 of diaphragm B4 toward the inlet of nozzle 54 and toclose the nozzle when the engine is' not running to prevent thedischarge of fuel. The diaphragm is marginally clamped in positionbetween casing 62 and the periphery of chamber 52 on the carburetor body8 by any conventional securing means, for example, machine screws whichare not illustrated in the drawing.

The pressure of the fuel in passage 56 is controlled by varying theeffective area of orifice 68 whichA permits more or less high pressurefuel from the outlet of pump 46 to enter the passa-ge 56, the path forflow of said fuel being from pump lll, through extension 48' of passage48, to orifice 68, and through chamber 69 into the extension 56 ofpassage 56. The means for varying the effective size of orifice 68comprises a tapered valve l!!4 gine is being started. A manuallyoperated primer is shown generally at 94 and consists of a. cylinder 96,piston 98, fuel passage |60 connecting cylinder 96 to the passage 55 anda. discharge passage i2 leading from the end of cylinder 98 to dischargenozzle 5l and having a spring loaded ball check valve iM disposedtherein'. The piston is urged -to the position shown in the drawing byspring 06 mounted on rod Hi8 between the end of cylinder 96 and controlnob H0. Fuel drawn from the fuel supply line 36 through passages 56 and|00 into the cylinder is entrapped in the forward end of the cylinder asthe forward movement of piston 98 closes passage |09 and is forcedthrough passage iil2 and discharge nozzle 54 into the induction passageI0. The spring in the cheek valve is sufficiently strong to prevent theflow of fuel in either direction through passage adapted to movelongitudinally in orifice -68 and connected to or formed integrally withfluted valve stem 12 which is adapted to move longitudinally in guide14, said stem being secured at its outer end to a flexible diaphragm 'i6by the deformation of the outer end 'i6 of stem 12 around vthe aperturesin the diaphragm 16 and stiifening members 80. The stiffening memberswhich are provided to render the central portion of diaphragm 16inflexible consist of a metal plate scoured to either side of thediaphragm by the outer end of stem 12, the edges of said plates beingrolled outwardly to prevent the diaphragm from being `punctured orotherwise injured by sharp edges or burs on the plate. In the assembledfuel system. diaphragm 16, which is of rubber-like material impermeableto fuel is secured in place `by the marginal edge thereof being clampedbetween the edge of casing 82 and the body of regulator i6. Chamber 84communicates with passage 48' and is therefore subjected to theunmetered fuel pressure posterior to impeller 42; thus, during theoperation of the engine, daphragm 1671s urged outwardly and valve 'i0 isurged toward its open position.

The position of valve 'Ill in orice 68 ls controlled in accordance withthe position of throttle valve idthrough cam 86 mounted on throttleshaft 88 and securedrigidly thereto by nut 99. The effective area oforifice 68 is decreased by the movementof valve 10 and valve stem 12 tothe right, as shown in Figure l. when the throttle valve is opened bvthe operator. The throttle valve is actuated by the accelerator pedallever or any equivalent thereof or controlled by a governor' through anywell known connecting means, which may be joined to lever 92 mounted onthe A priming means may be included in the fuel system to give anenriched mixture while the enouter i |92 except when piston 98' isdelivering fuel to passage l92.

The operation In the normal operation of the internal combustion engineemploying the present fuel sys- Atem, liquid fuel is delivered by pumpi8 or any suitable equivalent thereof to inlet passage 36 of the fuelregulator unit and thence through passage Sil'to the impcller l2 of pump40. The fuel received by pump 40 is discharged under increased pressureinto passage 48 from which it flows through metering orifice 59 and intothe chamber 52 urging diaphragm 64 away from the inlet of nozzle 54 topermit the fuel to discharge into induction passage i0.

Due to the inherent characteristics of the centrifugal pump 49, thepressure of the fuel in the outlet of the pump will be greater than thepump inlet pressure by an amount directly proportional to the square ofvthe speed of the pump and therefore proportional tothe square of theengine speed.

When throttle i4 is partially opened, the effective size of -orice 68 isrestricted to a value less than that at closed .throttle by taperedvalve 10. said valve and adjoining valve stem being held in a partiallyopened position by cam 86 contacting head 18 of the valve stem. As aresult, the flow of fuel Vthrough orifice 68 into passage 56, which isin communication with chamber 60 behind diaphragm 64, will be such thatthe pressure in said chamber will be of a value intermediate the fuelpressure on the inlet and outlet sides of the impeller of pump lill. Thevalue of this intermediate pressure in reference to said inlet and4outlet pressures will depend upon the effective areas of orifice 6Brelative to orifice 58. Consequently, if orifice 68 has an effectivearea equal to orifice 58, the pressure in'passage 56 will remainsubstantially half-way between the pressure of the fuel anterior to theimpeller and that of the unmetered fuel posterior to the impellerirrespective of variations in the speed of mpeller 42. The differencebetween .the pressure of the unmetered fuel posterior to the impellerand the pressure in passage 56 therefore will vary as the square of theengine speed for any fixed setting of valve '10.

The pressure of the metered fuel in chamber 52 on one side of diaphragm64 and the pressure of the fuel in chamber 60 on the other side of thediaphragm will be maintained substantially equal throughout theoperation of the engine. In the event the pressure ofthe metered fuel inchamber 52 should tend .to exceed the pressure of that behind diaphragm:64 as a result of' increased fuel delivered by the impeller, thediaphragm will move away from the nozzle inlet permitting the excessfuel to discharge int-o the induction passage at an increased rate suchthat .the pressures on either side of the diaphragm will again 'becomesubstantially equalized. Should the pressure o f the fuel behind thediaphragm in chamber Vlill. exceed that oi the metered fuel, thediaphragm will move toward the nozzle inlet restricting the discharge offuel from chamber 52 and consequently permitting the pressure in chamber52 -to increase until it is'equal to the pressure behind the diaphragm.Itis therefore apparent that .the difference between the pressure inchamber 52 land the pressure in passage 48 likewise will vary directlyas the engine speed. In view of the fact `that the Weight of airflowing-into an engine at a given throttle position varies substantiallyin direct proportion to the engine speed, except for variations causedby variables such as exhaust back pressure and intake air, the deviceherein described will supply fuel to the engine in accordance with airflowing thereinto as modified by throttle position.

Upon decrease in the effective area of orifice 68 with opening movementof the throttle, pressure in passage 56 will be reduced so as to morenearly approach the pressure anterior to impeller t2 and as a result,the diaphragm 6d will shift away from nozzle 5d to permit discharge offuel into the induction passage ata greater rate such that the pressurein chamber 52 will be reduced to equal the new pressure in passage 5S.In other words, reducing pressure in passage 56 reduces the pressure inchamber 52 and thereby increases the differential between the meteredand unmetered fuel in conduit 48. The fuel therefore is deliveredthrough jet 50 at a greater rate to compensate for the increase in airflow which results when the throttleis opened. By properly shaping valveor cam 84 the effective area of orifice 68 may be so controlled as toobtain any desired fuel-to-air relationship for .variations in engineoperating conditions. The variations, such as power or idle enrichment,may be accomplished by contouring the valve 10 to give the desired flowof fuel through orifice 60 when the throttle valve is moved either toits wide open position or to its substantially. closed position totherebyprovide whatever mixture richness is desired. Further,

certain variations can also be accomplished by varying the contour ofcam 86. For example, the cam can be provided with a peripheral lobe atthe point contacting the end of stem 12 when the throttle is wideopen,'thus nearly closing valve 10 and consequently decreasing thepressure in passage 56. This therefore would cause an increase in thesupply of fuel to the engine to provide a rich mixture while theengineis operating at high speed or pulling under heavy load.

It is contemplated that other elements or devices than those shown inthe drawing may be included in the present fuel system to obtain variousdesired fuel-to-air relationship under diverse engine operationconditions. The economizer for power enrichment, the acceleration devicefor giving temporary enrichment when the throttle is opened, and thetemperature control for modifying the richness of the fuel mixture inaccordance with temperature of the engine, all of which are shown anddescribed in detail in our copending application Serial No. 607,290,filed July 27, 1945, may be included in the present fuel system eitherseparately or together, in any combination of the three devices, withoutdeparting from the scope of the present invention. Further, the fueldistributor and a plurality of fuel discharge nozzles such as thosedisclosed in our copending application Serial No, 609,230, filed August6, 1945, may be substituted for the single nozzle arrangement shown inthe present drawing. A mechanism responsive to variations in atmosphericpressure for varying the spee'd of the impeller relative to the enginespeed may also be included in combination with the fuel system to obtainafuel leaning or enriching effect for maintaining proper fuel-to-airratio under substan-I tial Variations in atmospheric pressure, such asthose occurring as a result of changes in altitude. Means forconveniently obtaining variations in the speed of the impeller relativeto engine speed are well known to those skilled in the art; for example,the impeller may be driven by the engine through a fluid drive or byvariable speed pulleys.

From the foregoing description of the present invention -it is apparentthat a comparatively sim- Yple fuel system has been developed to give,

throughout the normal operating range, a sub.- stantially constantfuel-to-air mixture ratio subject to such modification as may berequired to efiect variations in said ratio for maximum econlomy andpower .and idle enrichment. Although to the engine, a means driven bysaid engine forv varying the pressure of the vfuel in said conduit inaccordance with engine speed, a restriction in said conduit posterior tosaid first mentioned means for metering the fuel delivered to saidengine, and a means communicating with the inlet and outlet sides of thefirst mentioned means for controlling the metering head across saidrestriction, said last mentioned means being regulated in accordancewith throttle position.

2. A fuel feeding device for an engine, comprising a conduit adapted toreceive fuel from a source and to deliver the fuel to said engine, ameans for varying the pressure of the fuel in said conduit in accordancewith engine speed, a metering orifice in said conduit for metering thefuel delivered to said engine, a means communicating with the conduitanterior to said pressure varying means and with unmetered fuelposterior thereto for controlling the metering head across said orifice,said last mentioned means being regulated in accordance with throttleposition.

3. In a fuel supply system for an engine, a conduit having a dischargenozzle for delivering fuel to the engine, a means for supplying fuel tosaid conduit at a substantially constant pressure,

means for varying the pressure of the fuel in saidvarying means formetering the fuel delivered to said engine, and a means communicatingwith the conduit anterior to said pressure varying means and withunmetercd fuel posterior thereto for controlling the metering head,across said orice, said last mentioned means being regulated inaccordance with throttle position. f

4. A fuel feeding device for an engine having an induction passage witha throttle valve therein, comprising a conduit having a discharge nozzlein said induction passage for delivering fuel to the engine, a means forvarying the pressure of the fuel in said conduit in accordance withengine speed, a restriction in said conduit for metering the fueldelivered to said nozzle, and a means regulated by the throttleactuating means and communicating with the inlet and outlet sides of thefirst mentioned means for controlling-the metering head across saidrestriction.

5. In a fuel supplysystem for an engine having an induction passage witha. throttle Valve therein, a. conduit having a discharge nozzle in saidinduction passage for delivering fuel to the engine, a

means for varying the pressure of the fuel in saidconduit in accordancewith engine speed, a restriction in said conduit posterior to s aidpressure varying means for. metering the fuel tosaid nozzle, and a meansregulated by the throttle actuating means and communicating with theconduit anterior to said pressure varying means and with unmetercd fuelposterior thereto vfor controlling the metering head across saidrestriction.

6.' In a fuel supply system for an engine having an induction passagewith a throttle valve therein," a conduit having a discharge nozzle insaid indue tion passage, a. means vdriven by said engine for varying thepressure of the fuel in said vconduit in accordance with engine speed,an orifice lin said conduit posterior to said pressure varying means formetering the fuel delivered to said nozzle, a means communicating withthe inlet andoutlet sides of the pressure varying means for controllingthe metering head across said orifice and meansregulated by the throttleactuating means for regulating the metering head controlling means..

7. A fuel feeding device for an engine having an induction passage witha throttle valve therein, comprising a conduit having a discharge nozzlein said induction passage for delivering fuel to the engine, a means forvarying the pressure of the speed, an orifice in said conduit posteriorto said pressure varying means for metering the fuel delivered to saidengine, a means communicating with the conduit anterior to said pressurevarying means and with kunxnetcrecl fuel posterior thereto forcontrolling the metering head across said orifuel in said conduit inaccordance with engine tice. and a means regulated by theythrottieactuating means for regulating the metering head controllingmeans.

8. In a fuel supply system for an engine having an induction passagewith a throttlevalve therein, a conduit having a discharge nozzle insaid induction passage for delivering fuel to the engine,

a means for varying the pressure of the fuel in said conduit inaccordance with engine speed, an

. orifice in said conduit posterior to said pressure 1 passage to enrichthe ratio of fuel-to-air mixture during engine starting.

9. In a fuel supply system for an internal combustion engine or the likehaving an induction passage with a throttle valve therein, a conduithaving a discharge nozzle in said induction passage for delivering fuelto the engine, a pump for supplying fuel to said conduit at asubstantially constant pressure, a means driven by said,

engine for varying the pressure of the fuel in said conduit in an amountproportional to the square of the engine speed, an orifice in saidconduit posterior to said pressure varying means for metering the fueldelivered to said engine, a means communicating with the conduitanterior to said pressure varying v`means and with unmetered fuelposterior thereto for controlling the metering head across said orifice,and a means regulated by the throttle actuating means for regulating themetering head controlling means.

l0. A fuel supply system for an engine having an induction passage witha throttle valve therein, a conduit having a discharge nozzle in said-induction passage for delivering fuel to said engine, a pump forsupplying fuel to said con duit at a substantially constant pressure, acentrifugal pump driven by said engine for varying the pressure of thefuel in said conduit in accordance with engine speed, an orifice in saidconduit posterior to said centrifugal pump for metering the fueldelivered to said engine, a control passage communicating with theconduit anterior to said centrifugal pump and with a passage forunmetered fuel'posterior thereto and having a fuel metering orice neareach end thereof and means regulated by the throttle actuating means forvarying the effective size of one of said orifices to control thepressure in said conduit and thereby to control the quantity of fueldischarged into said induction passage.

11. A fuel supply system for an engine havin an induction passage with athrottle valve therein comprising, a conduit having a discharge nozzlein said induction passage for delivering fuel to the engine, a means forsupplying fuel to said conduit at a substantially constant pressure, acentrifugal pump driven by said engine for varying the pressure of thefuel in said conduit in an amount proportional to the square of theengine speed, an orifice in said conduit posterior to said centrifugalpump for metering the fuel delivered to said nozzle, a control passagecommunicating with the conduit anterior to said centrifugal pumpand withthe passage for unmetered fuel posteriorv thereto and having a meteringorifice near each end thereof and means actuated by the throttleactuatingk means for varying the effective size of one of said orificesto regulate the pressure in said control passage, the metered' fuelposterior to said centrifugal pump and the fuel in said control passagecom-i municating with opposite sides of a diaphragm controlling thedischarge nozzle, whereby the discharge of fuel into said inductionpassage is controlled in accordance with variations 1n the fuel pressureon either side of said diaphragm.

12. In a fuel feeding device for an engine, burner orlvthe like, acentrifugal pump having an inlet adapted to receive fuel from a sourceand a fuel discharge passage, a metering restriction in the dischargepassage, a valve in the passage posterior to the restriction, apassageway interconnecting the discharge passage and inlet of the pumpand having two calibrated restrictions in series therein, meansresponsive to variations in the pressure in said passageway between therestrictions for controlling said valve, a main control element forcontrolling the output of the engine, burner or the like, and meansoperated by movement of said element for varying the eective size of oneof said restrictions.

13. A fuel feeding device for an engine comprising an air supply conduithaving o. throttle therein, a. centrifugal impeller adapted to be drivenby the engine, a fuel inlet to the ixnpeller, a fuel outlet from theimpeller for supplying fuel to the engine, a metering orifice in theoutlet. a by-pass from the outlet anterior to the orice to the fuelinlet, said by-pass containing two restrictions in series therein, avalve in the outlet posterior to the metering restriction, meansresponsive tothe pressure in said by-pass between. the two restrictionsfor controlling said valve, an element for varying the eiective size ofat least one of said restrictions, and a mechanical 20 t connectionbetween the element and the throttle for controlling the position ofsaid element.

'f- BARFOD.

REFERENCES CH'JlEl-l) The following references are of record in the nieof this patent:

if l STATES PATENTS land n July 25, 1940

